Changes in hip mechanics during gait modification to reduce knee abduction moment.

First peak knee abduction moment (KAM) has been associated with the severity and progression of knee osteoarthritis (KOA). Gait modifications, including lateral trunk lean (TL), medial knee thrust (MKT), and reduced foot progression (FP) have decreased KAM. However, their effects on the hip joint are poorly understood. Reduced hip abduction moment has been found to be predictive of KOA progression and has been hypothesized to represent a decreased demand on the hip musculature. Lack of studies investigating changes in hip mechanics as a result of gait modification limits our understanding of their cumulative benefit, therefore, we investigated the effects of TL, MKT, and FP on internal hip abduction moment as well as rate change in net joint reaction force. Using real-time visual biofeedback, five trials were completed for each modification. Each modification target range was individualized to 3-5 SD greater (TL and FP) or lesser (MKT) than the participants mean baseline value. Kinematics and kinetics at the hip and knee were calculated at first peak KAM. Trunk lean and MKT decreased hip abduction moment compared to baseline (p < 0.001). Trunk lean increased rate change in net joint reaction force at both the hip (p < 0.001) and knee (p < 0.001) compared to baseline. Additional research is needed to fully understand the effect of gait modifications in a clinical population, particularly the relationship between hip abduction moments and KOA progression. Although interventions such as MKT and TL can be successful in reducing KAM, their effects on hip abduction moment should be considered before clinical implementation.